PHOTOCHEMISTRY OF 2‐MERCAPTOPYRIDINES. PART 3. EPR STUDY OF PHOTOPRODUCTION OF HYDROXYL RADICALS BY N‐HYDROXYPYRIDINE‐2‐THIONE USING 5,5‐DIMETHYL‐1‐PYRROLINE N‐OXIDE IN AQUEOUS SOLUTIONS*

摘要: —N-Hydroxypyridine-2-thione, 2-S-PyrNOH, a potent antimicrobial, antifungal and anticancer agent, is photochemically active upon UV irradiation generates free radicals. We have employed EPR the spin-trap 5,5-dimethyl-l-pyrroline TV-oxide (DMPO) to investigate photochemistry in aqueous solutions of 2-S-PyrNOH (used here form sodium salt, 2-S-PyrNONa). found that photoactivation 2-S-PyrNONa can follow two different pathways: it produce hydroxyl radicals and/or act as photoreducing agent. The capacity “OH” has been demonstrated by: (1) detection DMPO/OH adduct UV-irradiated samples; (2) inhibition formation by OH scavengers such methyl alcohol, formate DMSO (3) signals DMPO adducts with derived from reaction these inhibitors. photoreductive was deduced observation amplitude signal spin decreased on air-free pH 7.0 buffers recovered dark after aeration. ability generate suggests be regarded potential photocytotoxic This feature may relevant biological action this compound. Our findings also emphasize caution should used when source or chemical systems.